Voltage pulse generator controlled solid state ignition system



Sept. 19, 1967- R. a. TARTER 3,342,167

VOLTAGE PULSE GENERATOR CONTROLLED SOLID STATE IGNITION SYSTEM Filed July 16, 1965 BYCIRIW His Attorney United States Patent 3,342,167 VOLTAGE PULSE GENERATOR CONTROLLED SOLID STATE IGNITION SYSTEM Ralph E. Tarter, Plano, Tex., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed July 16, 1965, Ser. No. 472,604 6 Claims. (Cl. 123--148) ABSTRACT OF THE DISCLOSURE This invention relates to a semiconductor ignition system for internal combustion engines which is controlled by a voltage pulse generator.

One of the objects of the present invention is to provide a magnetic triggered solid state ignition. system controlled by a voltage pulse generator where the output coil of the generator is connected with the ignition power source and where a voltage pulse is induced in the output coil to cause a firing of the spark plug at the instant of time where current that is supplied to the coil from the power source is at a minimum.

Another object of this invention is to provide a magnetic triggered solid state ignition system which prevents engine timing from being retarded as the engine speed increases. In carrying this object forward, the system is arranged such that the conduction of various semiconductors in the system are out of phase to thereby prevent a lagging signal frorn being induced in the coil of the pulse generator which otherwise would have the effect of retarding ignition timing as engine speed increases.

Still another object of this invention is to provide an ignition system for an internal combustion engine wherein a gate cont-rolled switch controls primary winding current and where the conduction of the gate controlled switch is controlled by at lea-st two transistors and a voltage pulse generator, the transistor being operated out of phase with the gate-controlled switch to prevent a retarding of spark timing during increases in engine speed.

Further objects and advantages of the present invention will be apparent from the following description reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

ductor 12 can be connected witha conductor 14 either through conductor 16 or through resistor 18 depending I upon the position of an ignition switch 20.

The ignition system includes an ignition coil. 22 having a primary winding 24 and a secondary winding 26. The

. primary and secondary windings are connected together at junction 28 and this junction is grounded through resistor 30. The opposite side of secondary winding 26 is connected with a high voltage conductor 32 which goes to the center electrode of a distributor cap 34. The distributor cap has conductive inserts 36 which are connected individually to the spark plugs 38 of an internal combustion engine 40 only one of which is illustrated in. the drawing.

The conductive inserts 36 are sequentially connected with high voltage conductor 32 by a. conventional rotor contact 42 driven in sychronism with the engine as is indicated in the drawing by the dotted lines.

The engine 40 also drives the rotor 44 of a voltage pulse generator generally designated by reference numeral 46. The voltage pulse generator may be part of a distributor where the shaft of the distributor is driven by the cam shaft of the engine 40 and where both the rotor 44 and rotor contact 42 are driven by the shaft.

Voltage pulse generator 46 includes a magnetic core 48 that carries an output coil 50. The magnetic core 48 provides a flux path for flux generated by a permanent magnet 52. As the magnetic rotor 44 rotates, an alternating voltage is induced in the output coil 50 which is used to trigger the ignition system of this invention as will be more .fully described.

The current for primary winding 24 is controlled by a 'gate controlled switch 54 having an anode connected with conductor 14 and a cathode connected with junction 56. The gate of the gate controlled switch 54 is connected with one side of capacitor 58. The opposite side of capacitor 58 is connected to one side of a secondary winding 60 of a pulse transformer 62 having a primary winding 64. The opposite side of the secondary winding 60 is connected with junction 56.

The gate controlled switch 54 is a PNPN semiconductor device which is triggered to a conductive condition between its anode and cathode when the vpotential of its gate is higher than its cathode. Once this is done, the gate signal can be removed and the gate controlled switch will conduct in its forward conduction. The gate controlled switch 54 is turned ofif when the potential of the cathode "is higher than the'potential of the gate. Once this isdone,

. connected with conductor 14 and with a junction 66. The

junction 66 is connected to a collector of the NPN transistor 68. The emitter of transistor 68 is connected to ground while the base of transistor 68 is connected with junction 70. A resistor 72 is connected across the base and emitter of transistor 68 The ignition system of this invention utilizes a PNP transistor 74. The emitter of transistor 74 is connected with. conductor 14 by a conductor 76. The collector of transistor 74 is connected with junction through a resistor 78. The base of transistor 74 is connected with junction and this junction is connected to one side of the output coil 56 by a conductor 82. The opposite side of the output coil 50 is connected with a junction 84.

The junction 84 is connected to one side of a diode 86,

i the opposite side of the diode being connected to junction 88. Another diode is connected between conductor 14 The junction 84 is connected with a junction 96 which .2 is connected to one side of a capacitor 98 and to one side of a resistor 100. The opposite side of the capacitor 98 is connected to conductor 14 while the opposite side of resistor 188 is grounded.

The operation of the ignition system of this invention will now be described. When the ignition system is energized as when switch 20 is closed, direct current is applied to the ignition system between conductor 14 and ground. When resistor 18 is in the circuit, the voltage applied to the system is lower and this circuit is used during a running condition of the engine. The conductor 16 is used when the engine is being cranked.

During a steady state condition, the transistors 74 and 68 are both biased to a conductive condition by current fiow from conductor 14, through the emitter to base circuit of transistor 74, through output 58, through junctions 84 and 96 and then through resistor 100 to ground. With base current flowing in transistor 74, this transistor turns on in it emitter-collector circuit so that current can also flow from conductor 14, through conductor 76, through the emitter to collector circuit of transistor 74, through resistor 78, and through resistor 72 to ground. The voltage developed across resistor 72 will bias the transistor 68 to a conductive condition in its collectoremitter circuit. When transistor 68 turns on, current can flow from conductor 14, through the primary 64 of the pulse transformer 62, and then through the collectoremitter circuit of transistor 68 to ground.

In this steady state condition, current will also flow from conductor 14, through diode 90, through resistor 92, through capacitor 94, and through the collector to emitter circuit of transistor 68 thereby charging capacitor 94 to system voltage. The capacitor 98 is charged to a voltage proportional to the voltage across diodes 90 and 86 through resistor 100.

When the rotor 44 is rotating either when the engine is being cranked or when the engine is running, an alternating voltage is induced in the pick-up coil 50. When the voltage at junction 80 is more positive than the voltage at junction 84, the transistor 74 will be reverse biased and this transistor therefore will be nonconductive to interrupt current flow through resistor 78 and resistor 72. This interrupt the supply of base current to transistor 68 with the result that transistor 68 turns oif when transistor 74 turns off.

When transistor 68 turns off, it interrupts current flow through the primary 64 of the pulse transformer 62 and as a result, a voltage is induced in the secondary 60 of a polarity such that junction 59 is more positive than junction 61. A pulse current will now flow through capacitor 58 and through the gate to cathode junction of the gate controlled switch 54 turning the gate controlled switch on in its anode-cathode circuit. Current will now flow from conductor 14, through the anode-cathode circuit of gate controlled switch 54, through primary 24 and through the resistor 30 to ground. The gate controlled switch 54 will remain in this conductive condition until such time that the voltage of the gate is more negative than the voltage at its cathode.

When the junction 59 is positive with respect to junction 61, the capacitor 58 will charge to the potential difference between these junctions when the gate controlled switch 54 turn on. The induced voltage in the primary 64 which causes junction 66 to become more positive than conductor 14 aids in discharging capacitor 94 through resistor 92, diode 86 and capacitor 98.

'As the rotor 44 continues to rotate, a voltage Will be induced in the pick-up coil 50 of such a magnitude and polarity that the junction 80 becomes more negative than junction 84. This will bias the transistor 74 to a conductive condition which will cause the transistor 68 to turn on. The voltage across the primary 64 of transformer 62 is such that conductor 14 is more positive than junction 66. This induces a voltage in the secondary 60 such that junction 61 becomes more positive than junction 59.

This voltage is sufficient to make the cathode of the gate controlled switch 54 more positive than the gate and current will flow from the gate through capacitor 58 and through the secondary 60 of the coupling transformer 62 thus turning the gate controlled switch 54 off and discharging capacitor 58.

It should be noted that transistors 68 and 74 operate out of phase with the gate controlled switch 54. This means that when junction is more positive than junction 84, the gate controlled switch 54 is on and current flows through the primary of the ignition coil 62. This arrangement prevents a turn-off pulse from being generated in output coil 50 which would have the effect of turning off gate controlled switch 54 at the time when current i flowing in coil 50 from battery 10. As a result, this arrangement prevents the development of a lagging signal from the pick-up coil 50 which would occur if battery current were flowing through the output coil 50 when current is flowing through the primary of the ignition coil 62. A lagging signal from the pick-up coil 50 would otherwise be caused by the induced voltages having a direction such that the currents produced would oppose the effect which produced them. The lagging signal from the pick-up coil 50 must be prevented since the amount of lagging increases with increasing speed of the rotor 44 and engine timing would be retarded as the engine speed increases were it not for the out of phase relationship of transistors 68 and 74 as compared with the conduction of gate controlled switch 54 and the fact that the turn-off signal for gate controlled switch 54 is generated at a time when battery current is not being supplied to coil 50.

It will be appreciated that whenever transistor 74 becomes forward biased by the voltage induced in output coil 50, that is, junction 80 becomes more negative than junction 84 at the greatest slope of the voltage wave form coming from pick-up coil 50, the gate controlled switch 54 turns off thus interrupting the current through the primary of the ignition coil. This change in current induces a voltage in the secondary 60 of the ignition coil 62 which is used to fire one of the spark plugs of the engine 40.

While the embodiments of the present invention as herein disclosed constitute a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. An ignition system for an internal combustion engine comprising, a source of direct current, an ignition coil having a primary winding and a secondary winding, a gate controlled switch having an anode, cathode and gate, means connecting the anode and cathode of said gate controlled switch and said primary winding in series across said source of direct current, first and second transistors, a transformer having a primary and a secondary, means connecting said secondary across the gate and cathode of said gate controlled switch, means connecting said primary and one of said transistors in series across said source of direct current, a voltage generating device including a rotatable element driven by said engine and an output coil, means connecting said output coil with said second transistor, means connecting said second transistor across said source of direct current, and means connecting said transistors whereby said transistors are both either fully conductive or fully nonconductive at the same time, opposite polarity signals being provided from across said output coil to bias said second transistor conductive and nonconductive in accordance with the polarity of said signals, said transformer being so-arranged that said gate controlled switch is turned on when both of said transistors are turned oif and said gate controlled switch is turned oif when both of said transistors are turned on, the current flow through said output coil being suppressed by output coil signals having a polarity biasing said second transistor nonconductive thereby preventing lagging induced voltages in said output coil.

2. An ignition system for an internal combustion engine comprising, a gate controlled switch having an anode, cathode and gate, an ignition coil having a primary Winding and a secondary winding, a source of direct current, means connecting the anode and cathode of said gate controlled switch and said primary winding in series across said source of direct current, a pulse transformer having a primary winding and a secondary winding, means connecting said secondary winding of said pulse transformer across the gate and cathode of said gate controlled switch, a first transistor, means connecting said primary winding of said pulse transformer and said first transistor in series across said source of direct current, a second transistor, a voltage generating device including an output coil, said voltage generating device developing an alternating polarity signal voltage in said output coil in synchronism with operation of said engine, means connecting the emitter-base circuit of said second transistor and said output coil in series across said source of direct current, said alternating polarity signal providing a reference voltage at the base of said second transistor to alternately oppose current through said output coil from said source of direct current and bias said second transistor conductive, and means coupling said first and second transistors whereby said transistors are both either fully conductive and fully nonconductive, said gate controlled switch being triggered to a conductive condition when said transistors are nonconductive and being triggered to a nonconductive condition when said transistors are conductive and current through said output coil is at a minimum.

3. An ignition system for an internal combustion engine comprising, a source of direct current, an ignition coil having a primary winding and a secondary winding, a gate controlled switch having an anode, cathode and gate, means connecting the anode and cathode of said gate controlled switch and said primary winding in series across said source of direct current, a coupling transformer, first and second transistors, an alternating-current voltage generating device driven in synchronism with said engine having output terminals, means connecting the primary winding of said pulse transformer and said first transistor in series across said source of direct current, means connecting said secondary winding of said pulse transformer and a capacitor in series and across the gate and cathode of said gate controlled switch, means connecting the output terminals of said voltage generating device in controlling relationship with said second transistor, and means connecting said first and second transistors whereby said first and second transistors are both either conductive or nonconductive depending upon the polarity of voltage being developed by said voltage generating device, one polarity of said alternating-current voltage biasing said second transistor nonconductive while suppressing current flow from said source of direct current through said output coil, said gate controlled switch being biased to a conductive condition when said transistors are nonconductive and current flow through said output coil is at a minimum thereby preventing lagging induced voltages, said gate controlled switch being biased to a nonconductive condition when said transistors are conductive.

4. The ignition system according to claim 3 where one of the transistors is of the NPN type and the other transistor is of the PNP type.

5. An ignition system for an internal combustion engine comprising, a gate controlled switch having an anode, cathode and gate, an ignition coil having a primary winding and a secondary winding, a source of direct current, mean connecting the anode and cathode of said gate controlled switch and said primary winding of said ignition coil in series across said source of direct current, a pulse transformer having a primary winding and a secondary winding, means connecting the secondary winding of said pulse transformer across the gate and cathode of said gate controlled switch, a first transistor of the NPN type, means connecting the primary winding of said pulse transformer and the collector and emitter electrodes of said first transistor in series across said source of direct current, an alternating-current voltage generating device driven by said engine having an output coil, a second transistor of the PNP type, a circuit. connected across said source of direct current including the emitter and base electrodes of said second transistor and said output coil, one polarity of said alternating-current voltage biasing said second transistor nonconductive and opposing current from said source of direct current through said output coil to suppress lagging induced voltages in said output coil, said last-named circuit including a junction, a pair of diodes connected in series between said junction and one side of said source of direct current, means connecting a junction point of said diodes to one side of the primary winding of said pulse transformer including a capacitor, and mean connecting the collector of said second transistor with the base of said first transistor.

6. The ignition system according to claim 5 Where a capacitor is connected in parallel with said pair of diodes.

References Cited UNITED STATES PATENTS 3,087,090 4/1963 Konopa 3l5209 3,277,340 10/1966 Jukes et al 123148 LAURENCE M. GOODRIDGE, Primaiy Examiner. 

1. AN IGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING, A SOURCE OF DIRECT CURRENT, AN IGNITION COIL HAVING A PRIMARY WINDING AND A SECONDARY WINDING, A GATE CONTROLLED SWITCH HAVING AN ANODE, CATHODE AND GATE, MEANS CONNECTING THE ANODE AND CATHODE OF SAID GATE CONTROLLED SWITCH AND SAID PRIMARY WINDING IN SERIES ACROSS SAID SOURCE OF DIRECT CURRENT, FIRST AND SECOND TRANSISTORS, A TRANSFORMER HAVING A PRIMARY AND A SECONDARY, MEANS CONNECTING SAID SECONDARY ACROSS THE GATE AND CATHODE OF SAID GATE CONTROLLED SWITCH, MEANS CONNECTING SAID PRIMARY AND ONE OF SAID TRANSISTORS IN SERIES ACROSS SAID SOURCE OF DIRECT CURRENT, A VOLTAGE GENERATING DEVICE INCLUDING A ROTATABLE ELEMENT DRIVEN BY SAID ENGINE AND AN OUTPUT COIL, MEANS CONNECTING SAID OUTPUT COIL WITH SAID SECOND TRANSISTOR, MEANS CONNECTING SAID SECOND TRANSISTOR ACROSS SAID SOURCE OF DIRECT CURRENT, AND MEANS CONNECTING SAID TRANSISTORS WHEREBY SAID TRANSISTORS ARE BOTH EITHER FULLY CONDUCTIVE OR FULLY NONCONDUCTIVE AT THE SAME TIME, OPPOSITE POLARITY SIGNALS BEING PROVIDED FROM ACROSS SAID OUTPUT COIL TO BIAS SAID SECOND TRANSISTOR CONDUCTIVE AND NONCONDUCTIVE IN ACCORDANCE WITH THE POLARITY OF SAID SIGNALS, SAID TRANSFORMER BEING SO-ARRANGED THAT SAID GATE CONTROLLED SWITCH IS TURNED ON WHEN BOTH OF SAID TRANSISTORS ARE TURNED OFF AND SAID GATE CONTROLLED SWITCH IS TURNED OFF WHEN BOTH OF SAID TRANSISTORS ARE TURNED ON, THE CURRENT FLOW THROUGH SAID OUTPUT COIL BEING SUPPRESSED BY OUTPUT COIL SIGNALS HAVING A POLARITY BIASING SAID SECOND TRANSISTOR NONCONDUCTIVE THEREBY PREVENTING LAGGING INDUCED VOLTAGE IN SAID OUTPUT COIL. 